The present application relates generally to a dot-sighting device with a beam splitter.
The performance of rifles or heavy machine guns depends on how fast an aimed shot is accurately fired. Generally, rifles or heavy machine guns (hereinafter, referred to as collectively a “gun”) are aimed by aligning the sight positioned on the body thereof with the front sight positioned on the muzzle thereof. When a target is aimed by aligning the sight with the front sight, the user is likely to accurately fire the gun though it depends on the user's skill whether or not the target is accurately hit.
However, when the gun slightly vibrates or is slightly shaken, it is difficult to align a line of sight using the sight and the front sight, and it is difficult to rapidly aim a target at a short distance or in an urgent situation.
In this aiming and firing method, not only is a complicated aiming process of capturing and checking a target and aligning a line of sight required, but also it takes time. Particularly, since the sight and the front sight are too small and sensitive, it is difficult for the user to align the sight with the front sight when even slight vibration occurs. Further, when the user excessively pays attention to alignment of a line of sight, the user's eyes are focused on the sight and the front sight rather than a situation occurring in front, and thus the user's field of view necessary to fire or deal with an urgent situation is narrowed.
In order to resolve difficulty in aligning a line of sight and improve the aiming accuracy, a sighting device with a telescopic lens has been proposed. However, a high-power optical sighting device with a telescopic lens is sensitive even to slight vibration, and thus it is not easy to rapidly aim.
In this regard, a dot-sighting device configured such that an optical sighting device employs a no-power lens or a low-power lens and uses an aiming point without a line of sight has been proposed.
The optical dot-sighting device with the no- or low-power lens helps the user rapidly aim a target and is useful at a short distance or in an urgent situation. Specifically, a time necessary to align a line of sight can be reduced, and since the user has only to match a dot reticle image with a real target, the user can be given a time enough to secure a field of vision. Thus, a target can be aimed rapidly and accurately, and a field of vision necessary to determine a surrounding situation can be secured.
However, in such a dot-sighting device, an optical axis of a reflective mirror is inclined to an optical axis of a barrel of the dot-sighting device and parallax is larger than in an optical system in which an optical axis of a reflective mirror matches an optical axis of a main tube. Further, in order to secure a region within allowable parallax, a distance between the dot reticle and the reflective mirror needs to be further increased, and the effective diameter of the reflective mirror needs to be further reduced.
In the dot-sighting device illustrated in FIG. 1, a dot reticle generating unit 5 is positioned not to hinder movement of light reflected from a reflective mirror 7. Light irradiated by the dot reticle generating unit 5 is not seen from the outside, and thus the user of the dot-sighting device is not noticed by an opponent party. To this end, the optical axis of the reflective mirror has to be inclined with respect to a principal ray (which is generally at the center among light rays and matches an optical axis of the dot-sighting device) which is a representative ray of light reflected from reflective mirror and forms a dot (an image of a dot reticle formed by the reflective mirror) at a predetermined angle (an angle A1 in FIG. 2A). Here, the angle A1 is ½ of an angle A2 formed by a path through the principal ray emitted from the dot reticle generating unit 5 is reflected by the reflective mirror 7 and moves along the optical axis of the dot-sighting device.
In this case, since the reflective mirror is arranged to be inclined to the optical axis of the dot-sighting device (FIG. 2A), large finite ray aberration occurs and affects parallax of a dot observed by the user. Thus, when the size (diameter) of the reflective mirror is assumed to be equal to the distance from the dot reticle generating unit 5 to the reflective mirror 7, the arrangement (FIG. 2A) of the reflective mirror 7 inclined to the optical axis of the dot-sighting device is larger in parallax than the arrangement (FIG. 2B) of the reflective mirror 7 that is not inclined to the optical axis of the dot-sighting device.
The large parallax is likely to increase an error on an initial alignment status among the optical axis of the dot-sighting device, a bullet firing axis of a gun barrel, and a target point as the user's visual axis on the firing target point in the reflective mirror deviates from the optical axis of the dot-sighting device and stays at the periphery of the reflective mirror.
Further, since the parallax increases as the distance between the dot reticle generating unit 5 and the reflective mirror 7 decreases, the structure illustrated in FIG. 2B is smaller in parallax than the structure illustrated in FIG. 2A. Thus, in the structure illustrated in FIG. 2B, the distance between the dot reticle generating unit 5 and the reflective mirror 7 can be reduced to be smaller than in the structure illustrated in FIG. 2A to the extent that the parallax occurs at the same level as in the structure illustrated in FIG. 2A, and thus the size of the dot-sighting device can be reduced.
However, in spite of the above advantages, in the structure illustrated in FIG. 2B, since the dot reticle generating unit 5 is positioned at the center of the barrel of the dot-sighting device, observation of an external target point is hindered, and it is difficult to rapidly aim the target. In addition, light generated from the dot reticle generating unit 5 is observed from the external target point or the opponent party around it, and thus the position of the user of the dot-sighting device is likely to be exposed to the opponent part.